We ordered the thermal blanket for the Yoder 640S after smoking a pork shoulder on a January day where the high temperature was 6 degrees Fahrenheit. The 640S did a fine job on that cook but it went through an impressive amount of pellets. The next day we ordered the thermal blanket and had it just a few days later. It fits like a glove and is quite easy to install after watching Chef Tom’s helpful video. We haven’t cooked in those subzero conditions with the thermal blanket yet, but it has reduced our pellet consumption noticeably in 30-50 degree weather. The quality of this blanket, the fit and the ease of use are all first rate. Operation of the smoker is the same with the blanket on as it is off, so I may be leaving the blanket on year around.